A conventional art of this kind of electric booster is disclosed in Japanese Patent Application Public Disclosure No. 2008-302725. In the electric booster disclosed in Japanese Patent Application Public Disclosure No. 2008-302725, an electric motor, and an ECU (Electric Control unit) for supplying an electric current to a stator of the electric motor to control the electric motor are integrally provided. The electric motor is actuated in response to an actuation instruction from the ECU. The rotation of the electric motor is converted into a linear motion by a rotation-linear motion converting mechanism, and is transmitted to an output member which then causes a piston of a master cylinder to advance, thereby generating a brake fluid pressure in a pressure chamber in the master cylinder.
In the above-mentioned conventional electric booster, the ECU for controlling the electric motor is disposed at a front-side casing member (first casing), while the stator of the electric motor is disposed at a rear-side casing member (second housing) which covers the opening of the front-side casing member at the rear end thereof. As a result, the wiring process for connecting the ECU and the stator is troublesome in this electric booster.